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Hepatic hydatid disease (or hepatic echinococcosis) is a parasitic infection of the liver caused by the larval stage of Echinococcus species, most commonly Echinococcus granulosus (causing cystic echinococcosis*).

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Less commonly, Echinococcus multilocularis causes alveolar echinococcosis, a more infiltrative and aggressive variant.

Epidemiology

Pathophysiology

1. Life cycle:
   • Humans ingest Echinococcus eggs → larvae penetrate intestinal mucosa → portal circulation → liver (first filter) → development of hydatid cysts.
   • Growth rate: ~1–3 cm/year.
   • Cysts contain viable scolices and daughter cysts within fluid-filled cavities.
2. Cyst structure (for E. granulosus):
   • Outer pericyst (host-derived fibrous capsule)
   • Middle laminated membrane (acellular)
   • Inner germinal layer (endocyst) — produces brood capsules and daughter cysts.
3. E. multilocularis causes multivesicular, infiltrative lesions without a well-defined capsule → mimics malignancy.

Clinical Features

• Palpable mass- Hepatomegaly | | Complications | - Cyst rupture → anaphylaxis or dissemination
• Secondary bacterial infection → abscess
• Biliary communication → obstructive jaundice
• Pressure effects (portal hypertension, cholangitis) |

Laboratory Findings

• Eosinophilia (in ~20–25%)
• Serology (ELISA, indirect hemagglutination, immunoblot): Supportive, not diagnostic alone.
• Liver function tests: May show cholestasis if biliary rupture.

Imaging Evaluation